When I taught high school, the clay teacher made a mural with the kids and
here are some of the things I remember him doing:
* tell the kids not to bend the edges if possible because the clay has a
memory and will curl when drying
* dry the tiles on an elevated screen so that they get air flow all around
* attach to a plywood or masonite backing using a strong adhesive like Liquid
Nails
* Hang on the wall using two L-shaped brackets drilled into studs (one
L-shaped bracket on the wall, the other on the back of the mural and they lock
into place)